Technical Field
The present disclosure is directed to a microfluidic system configured to eject fluids from a plurality of nozzles driven in groups, where each nozzle of one group is driven with a single drive signal.
Description of the Related Art
Microfluidic systems include a variety of ejection techniques that cause fluid to exit nozzles of a die. These techniques includes thermal, piezo, and ultrasonic, to name a few. One example is thermal inkjet print heads, which have precise nozzle control to deliver a drop of ink onto a piece of paper in a very precise location. In order to achieve this precision, control of each nozzle is associated with a single, dedicated electrical connection.
Many of these systems have such dedicated external electrical connections for each nozzle in the die, such that if there are N nozzles, there are N+1 external electrical connections. The extra connection being coupled to ground. The external electrical connections may be a flexible conduit of wires that couple to bond pads of the die. These systems also often have a dedicated internal electrical connection on the die for each nozzle, each internal electrical connection being coupled to one of the bond pads of the die. These arrangements can be referred to as the direct drive of each nozzle. These die tend to be large because of the number of bond pads and internal electrical connections utilized.
More complicated ejection systems include rows and columns of nozzles that are controlled by active circuitry formed in the same substrate as the nozzles. The active circuitry could include NMOS transistors that multiplex the rows and columns to allow for more nozzles to be controlled by a single one of the bond pads.
Further involved systems integrate CMOS based logic to create clock systems to change the bond pad to nozzle ratio for each die. In order to form the CMOS based logic on the die, the die becomes extremely complicated and costly to manufacture. Layers upon layers of thin films are added to modify the bond pad to nozzle ratio.